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April 3rd 04, 07:16 PM

On Sat, 3 Apr 2004 11:25:34 -0600 (CST),
(Richard Harrison) wrote:
Kraus says on page 229 of his 1950 edition:
"Whereas the characteristic impedance of a biconical antenna is uniform,
the impedance of antennas of shapes other than conical is nonuniform."

Hi Richard,

This analysis is derived from Schelkunoff's work that was later (1952)
offered in his "Advanced Antenna Theory." This material is offered in
a more accessible form in "Antennas and Radiowave Propagation," Robert
E. Collin, 1985 with the following observation:
"In his book Schelkunoff shows .... the biconical antenna theory
provides a theoretical basis for assuming a sinusoidal current
distribution on thin-wire antennas."

Basically, the biconical antenna theory is the basis for the
fundamental treatment of antenna as a non-terminated transmission line
by which all thin-wire antennas may be shown to devolve from (as the
degenerate forms of infinitely small radius cone sections). Such
treatment allows those interested to observe both the SWR relationship
(E/I distribution) of thin-wire elements compared to what you
correctly identify as the uniform impedance of the large cone angle
forms and both be mathematically consistent with such diverging
characteristics (which is to say those who oppose the discussion of
Antenna as transmission line are unaware of this work).

However, as to its application in a Yagi-Uda design, it has to be
particularly unrewarding as nearby elements preclude a full-blown
conic development without the attending physical interference.

73's
Richard Clark, KB7QHC

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